The onset and growth of the 1990 equatorial disturbance on Saturn

The development of cloud structures at low Saturnian latitudes in September 1990 can be divided into three phases: the onset and expansion of the initial disturbance (popularly known as the Great White Spot), the eastward and westward expansion of the bright cloud, and the eventual formation of wave-like structures encircling the equator. The three phases of this storm are consistent with a single convective event. This event is evaluated within the historical context of previous occurrences and general seasonal mechanisms are considered.